Natarajan et al. in Australian Patent Application 17,203 disclose acylalkylaminocarbonyl substituted amino and imino acid compounds of the formula ##STR2## wherein R.sub.2 is certain aryl, aralkyl, hetero, or alkylene-hetero groups. These compounds possess angiotensin converting enzyme inhibition activity and enkephalinase inhibition activity depending upon the definition of X.
Almquist et al. in U.S. Pat. No. 4,329,473 disclose angiotensin converting enzyme inhibiting compounds of the formula ##STR3## wherein R.sub.2 is aryl, alkyl, alkoxy or benzyloxy.